Printing of conductive materials has been accomplished in many different ways. Further, various methods for manufacturing printed circuit boards are known. In recent years, new methods have been developed to form thin metallic layers to be used as antenna elements or other electrical circuit components, in particular by applying a conductive liquid, sometimes referred to as a conductive paint or ink, onto a substrate or support member.
One such method is the print and etch method. This method is used particularly for producing printed circuit boards where the conductive paths are applied only to one side of the board, for example, printed circuits with low packing density. Additionally, the print and etch method can be carried out using a board of non-conductive material with a copper layer laminated to one or both sides of the board. The conductive structures of the printed circuit board may be applied by using, for example, screen-printing or photographic methods, e.g., applying photoresist, exposing, and developing.
Another very common current circuit printing method is screen-printing. This type of printing device generally comprises a silk screen plate set on an insulating base board to be printed, and an ink delivery device which runs on the screen plate while delivering a given amount of viscous conductive ink including a binder, often referred to as thick-film, onto the screen plate and pressing the same against the insulating base board. With this, on the surface of the insulating base board, there is printed a desired circuit pattern of the conductive ink that coincides with a perforated print pattern formed in the screen plate. The base board can then be heated for fixing the printed circuit pattern. The screen plate is usually constructed of a stainless steel, silk, or the like. However, there are drawbacks with screening methods related to the additional steps of cleaning the printed surface and screen, drying, achieving uniform thickness, and the wasting of excess paste.
Other methods of applying conductive materials to a surface include dipping, flooding, brushing, and spraying. For example, mixed powders slurried in water may be applied to a substrate by spraying or painting. The applied material can then be dried and heated at high temperature to yield a conductive glaze. Methods commonly used in the semiconductor fabrication industry include evaporation, sputtering, and traditional chemical vapor disposition.
Thermal ink jet printers are known to provide an effective means of propelling ink-jet inks onto various media. These printers can accomplish this by using resistive heater elements for heating the ink to a boil, and propelling the ink through an overlying orifice plate. There are several reasons that ink-jet printing has become a popular way of recording images on various media surfaces. Some of these reasons include low printer noise, capability of high-speed recording, multi-color recording, and a relatively low consumer price. However, though there has been great improvement in ink-jet printing, accompanying this improvement are increased demands by consumers in this area, e.g., higher speeds, higher resolution, full color image formation, increased stability, new applications, etc. Several of such new applications are provided herein.